The invention relates to optical communication, and, more particularly, to optical cross connect (OXC) designs for use in optical networks.
A leading technology for use in next generation high-speed communication networks has been wavelength division multiplexing (WDM) or its variations such as Dense-WDM. See, e.g., M. S. Borella, J. P. Jue, D. Banerjee, et al., “Optical Components for WDM Lightwave Networks,” Proceedings of the IEEE, Vol. 85, No. 8, pp. 1274-1307, August 1997, the contents of which are incorporated by reference herein. In a WDM system, multiple signal sources are emitted at different wavelengths and multiplexed onto the same optical medium, each wavelength representing a separate channel. A fundamental building block of a WDM network is the optical cross connect (OXC) which routes input optical signals entering the node to appropriate output ports. A variety of different approaches have been developed for the design of optical cross connects, including optical-electrical-optical (OEO) switches, all-optical (OO) switches and hybrid approaches that serve as a migration path to an all-optical switch.
An advantageous hybrid cross-connect design, referred to as a “hybrid hierarchical” optical cross connect architecture, bundles together groups of wavelengths with a similar switching path, referred to as a “waveband.” See co-pending U.S. Utility patent application, Ser. No. 10/100,990, entitled “NON-UNIFORM OPTICAL WAVEBAND AGGREGATOR AND DEAGGREGATOR AND HIERARCHICAL HYBRID OPTICAL CROSS-CONNECT SYSTEM”, filed on Mar. 20, 2002, published as 2003/0185565 on Oct. 2, 2003, the contents of which are hereby incorporated by reference herein. The separation of input wavebands and the assignment of each band to the OO or OEO plane is performed by what is referred to as a “waveband deaggregator/aggregator” (WDA). The WDA uses fixed wavelength filters to separate the wavebands and uses small switches to assign each waveband to appropriate planes. Signals can go directly from the WDA into an OEO switch without going through the OO switch first, thereby maximizing each switching plane's usage and increasing the node's switching efficiency.
It is advantageous to further improve the design of the waveband deaggregator/aggregator—in particular, to improve its intelligence, flexibility, and versatility while maintaining low cost and complexity.